class Solution:
    # 返回对应char
    char_map = {}
    temp_string = ''
    def FirstAppearingOnce(self):
        for key in self.temp_string:
            if self.char_map[key] == 1:
                return key
        return '#'

    def Insert(self, char):
        self.temp_string += char
        if char in self.char_map:
            self.char_map[char] += 1
        else:
            self.char_map[char] = 1
